1. Field of the Invention
The present invention relates to a mobile ballast cleaning machine for continuously receiving ballast from a ballast bed supported on a subgrade and supporting a track having two rails, and for cleaning the received ballast, which comprises a machine frame extending in a longitudinal direction along the track, undercarriages supporting the machine frame for mobility on the track in an operating direction, an excavating chain mounted on the machine frame and arranged to excavate the ballast to expose the subgrade, a ballast screening installation arranged to receive the excavated ballast from the excavating chain and to clean the received ballast, a conveyor arrangement for conveying the cleaned ballast for distribution on the exposed subgrade, and a power-actuated, vertically and transversely adjustable track lifting device mounted on the machine frame.
2. Description of the Prior Art
Such ballast cleaning machines are very well known, as exemplified by U.S. Pat. No. 3,685,589, dated Aug. 22, 1972, which discloses a ballast cleaning machine in which the machine frame is supported on the track at each end by undercarriages and an excavating chain is vertically and laterally adjustably mounted on the machine frame centrally between the undercarriages for excavating dirty and encrusted ballast and convey the excavated ballast upwardly to a vibratory ballast screening installation for cleaning the ballast. The waste component coming from the screening installation is conveyed by two independently operated conveyor bands to the respective ends of the machine frame while a further conveyor conveys the cleaned ballast component from the screening installation to a discharge end at the exposed subgrade immediately behind a transverse course of the excavating chain extending under the track. At this location, a power-actuated, vertically and laterally adjustable track lifting device on the machine frame lifts the track. Immediately behind this cleaned ballast discharge point, a second track lifting device is arranged on the machine frame to raise the track sufficiently to enable a vibratory ballast compactor to be inserted for engaging the surface of the cleaned ballast for smoothing and compacting the cleaned ballast discharged on the subgrade. A cleaned ballast discharge chute is disposed at the rear of the ballast screening installation for distributing a portion of the cleaned ballast in the cribs. While the cleaned ballast bed can be compacted with this machine, the disposition of the surface compactor requires a relatively high raising of the track.